Wireless electronic devices, such as notebook computers, mobile phones, and personal digital assistants (PDAs) typically employ an antenna for receiving and/or transmitting communication signals. Antennas have been mounted both externally and internally, but certain problems are associated with each approach. For example, mounting an antenna externally can create a less desirable form factor as well as increase the vulnerability of the antenna to damage from contact with external objects. On the other hand, mounting the antenna internally within the device can also be problematic due to space constraints and due to interference with transmission of the wireless signal. For example, metals (e.g., magnesium-aluminum alloys) are often employed in the construction of the device housing due to their stylish appearance and good surface feel. Because these metals exhibit electromagnetic interference (“EMI”) shielding, however, a portion of the housing must generally be made of plastic so that signals can be received and transmitted through the housing. This has been accomplished, for instance, by covering the antenna with a plastic component.
While helping to solve the problem of EMI shielding, the presence of the plastic component can lead to various additional problems. For example, because it is visible from the exterior of the device, the housing is often surface coated with a paint to help better match its color to that of the metal. This also helps to bond together the metal and plastic materials. Unfortunately, most plastic materials have a significantly different color than metals, which results in the need for a significant number of coatings to achieve the desired color. Moreover, the housing is also typically heated during application of a surface coating. Due to the significantly different thermal characteristics of the plastic and metal, however, such heating can result in a poor surface interface between the materials. This poor interface contributes to the need for an additional number of surface coatings to help achieve good bonding between the materials and a uniform appearance.
As such, a need currently exists for a material that is able to better match both the color and thermal characteristics of metals used in forming composite structures of electronic devices.